South Dakota is a U. S. state in the Midwestern region of the United States. It is named after the Lakota and Dakota Sioux Native American tribes, who compose a large portion of the population and dominated the territory. South Dakota is the seventeenth largest by area, but the fifth smallest by population and the 5th least densely populated of the 50 United States; as the southern part of the former Dakota Territory, South Dakota became a state on November 2, 1889 with North Dakota. Pierre is the state capital and Sioux Falls, with a population of about 187,200, is South Dakota's largest city. South Dakota is bordered by the states of North Dakota, Iowa, Nebraska and Montana; the state is bisected by the Missouri River, dividing South Dakota into two geographically and distinct halves, known to residents as "East River" and "West River". Eastern South Dakota is home to most of the state's population, the area's fertile soil is used to grow a variety of crops. West of the Missouri, ranching is the predominant agricultural activity, the economy is more dependent on tourism and defense spending.
Most of the Native American reservations are in West River. The Black Hills, a group of low pine-covered mountains sacred to the Sioux, are in the southwest part of the state. Mount Rushmore, a major tourist destination, is there. South Dakota has a temperate continental climate, with four distinct seasons and precipitation ranging from moderate in the east to semi-arid in the west; the state's ecology features species typical of a North American grassland biome. Humans have inhabited the area for several millennia, with the Sioux becoming dominant by the early 19th century. In the late 19th century, European-American settlement intensified after a gold rush in the Black Hills and the construction of railroads from the east. Encroaching miners and settlers triggered a number of Indian wars, ending with the Wounded Knee Massacre in 1890. Key events in the 20th century included the Dust Bowl and Great Depression, increased federal spending during the 1940s and 1950s for agriculture and defense, an industrialization of agriculture that has reduced family farming.
While several Democratic senators have represented South Dakota for multiple terms at the federal level, the state government is controlled by the Republican Party, whose nominees have carried South Dakota in each of the last 13 presidential elections. Dominated by an agricultural economy and a rural lifestyle, South Dakota has sought to diversify its economy in areas to attract and retain residents. South Dakota's history and rural character still influence the state's culture. South Dakota is in the north-central United States, is considered a part of the Midwest by the U. S. Census Bureau; the culture and geography of western South Dakota have more in common with the West than the Midwest. South Dakota has a total area of 77,116 square miles, making the state the 17th largest in the Union. Black Elk Peak named Harney Peak, with an elevation of 7,242 ft, is the state's highest point, while the shoreline of Big Stone Lake is the lowest, with an elevation of 966 ft. South Dakota is bordered to the north by North Dakota.
The geographical center of the U. S. is 17 miles west of Castle Rock in Butte County. The North American continental pole of inaccessibility is between Allen and Kyle, 1,024 mi from the nearest coastline; the Missouri River is the longest river in the state. Other major South Dakota rivers include the Cheyenne, Big Sioux, White Rivers. Eastern South Dakota has many natural lakes created by periods of glaciation. Additionally, dams on the Missouri River create four large reservoirs: Lake Oahe, Lake Sharpe, Lake Francis Case, Lewis and Clark Lake. South Dakota can be divided into three regions: eastern South Dakota, western South Dakota, the Black Hills; the Missouri River serves as a boundary in terms of geographic and political differences between eastern and western South Dakota. The geography of the Black Hills, long considered sacred by Native Americans, differs from its surroundings to such an extent it can be considered separate from the rest of western South Dakota. At times the Black Hills are combined with the rest of western South Dakota, people refer to the resulting two regions divided by the Missouri River as West River and East River.
Eastern South Dakota features higher precipitation and lower topography than the western part of the state. Smaller geographic regions of this area include the Coteau des Prairies, the Dissected Till Plains, the James River Valley; the Coteau des Prairies is a plateau bordered on the east by the Minnesota River Valley and on the west by the James River Basin. Further west, the James River Basin is low, flat eroded land, following the flow of the James River through South Dakota from north to south; the Dissected Till Plains, an area of rolling hills and fertile soil that covers much of Iowa and Nebraska, extends into the southeastern corner of South Dakota. Layers deposited during the Pleistocene epoch, starting around two million years ago, cover most of eastern South Dakota; these are the youngest rock and sediment layers in the state, the product of several successive periods of glaciation which deposited a large amount of rocks and soil, known as till, over the area. The Great Plains cover most of the western two-thirds of South Dakota.
West of the Missouri Rive
A telescope is an optical instrument that makes distant objects appear magnified by using an arrangement of lenses or curved mirrors and lenses, or various devices used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. The first known practical telescopes were refracting telescopes invented in the Netherlands at the beginning of the 17th century, by using glass lenses, they were used for both terrestrial applications and astronomy. The reflecting telescope, which uses mirrors to collect and focus light, was invented within a few decades of the first refracting telescope. In the 20th century, many new types of telescopes were invented, including radio telescopes in the 1930s and infrared telescopes in the 1960s; the word telescope now refers to a wide range of instruments capable of detecting different regions of the electromagnetic spectrum, in some cases other types of detectors. The word telescope was coined in 1611 by the Greek mathematician Giovanni Demisiani for one of Galileo Galilei's instruments presented at a banquet at the Accademia dei Lincei.
In the Starry Messenger, Galileo had used the term perspicillum. The earliest existing record of a telescope was a 1608 patent submitted to the government in the Netherlands by Middelburg spectacle maker Hans Lippershey for a refracting telescope; the actual inventor is unknown but word of it spread through Europe. Galileo heard about it and, in 1609, built his own version, made his telescopic observations of celestial objects; the idea that the objective, or light-gathering element, could be a mirror instead of a lens was being investigated soon after the invention of the refracting telescope. The potential advantages of using parabolic mirrors—reduction of spherical aberration and no chromatic aberration—led to many proposed designs and several attempts to build reflecting telescopes. In 1668, Isaac Newton built the first practical reflecting telescope, of a design which now bears his name, the Newtonian reflector; the invention of the achromatic lens in 1733 corrected color aberrations present in the simple lens and enabled the construction of shorter, more functional refracting telescopes.
Reflecting telescopes, though not limited by the color problems seen in refractors, were hampered by the use of fast tarnishing speculum metal mirrors employed during the 18th and early 19th century—a problem alleviated by the introduction of silver coated glass mirrors in 1857, aluminized mirrors in 1932. The maximum physical size limit for refracting telescopes is about 1 meter, dictating that the vast majority of large optical researching telescopes built since the turn of the 20th century have been reflectors; the largest reflecting telescopes have objectives larger than 10 m, work is underway on several 30-40m designs. The 20th century saw the development of telescopes that worked in a wide range of wavelengths from radio to gamma-rays; the first purpose built radio telescope went into operation in 1937. Since a large variety of complex astronomical instruments have been developed; the name "telescope" covers a wide range of instruments. Most detect electromagnetic radiation, but there are major differences in how astronomers must go about collecting light in different frequency bands.
Telescopes may be classified by the wavelengths of light they detect: X-ray telescopes, using shorter wavelengths than ultraviolet light Ultraviolet telescopes, using shorter wavelengths than visible light Optical telescopes, using visible light Infrared telescopes, using longer wavelengths than visible light Submillimetre telescopes, using longer wavelengths than infrared light Fresnel Imager, an optical lens technology X-ray optics, optics for certain X-ray wavelengthsAs wavelengths become longer, it becomes easier to use antenna technology to interact with electromagnetic radiation. The near-infrared can be collected much like visible light, however in the far-infrared and submillimetre range, telescopes can operate more like a radio telescope. For example, the James Clerk Maxwell Telescope observes from wavelengths from 3 μm to 2000 μm, but uses a parabolic aluminum antenna. On the other hand, the Spitzer Space Telescope, observing from about 3 μm to 180 μm uses a mirror. Using reflecting optics, the Hubble Space Telescope with Wide Field Camera 3 can observe in the frequency range from about 0.2 μm to 1.7 μm.
With photons of the shorter wavelengths, with the higher frequencies, glancing-incident optics, rather than reflecting optics are used. Telescopes such as TRACE and SOHO use special mirrors to reflect Extreme ultraviolet, producing higher resolution and brighter images than are otherwise possible. A larger aperture does not just mean that more light is collected, it enables a finer angular resolution. Telescopes may be classified by location: ground telescope, space telescope, or flying telescope, they may be classified by whether they are operated by professional astronomers or amateur astronomers. A vehicle or permanent campus containing one or more telescopes or other instruments is called an observatory. An optical telescope gathers and focuses light from the visible part of the electromagnetic spectrum. Optical telescopes increase the apparent angular size of distant objects as well as their apparent brightness. In order for the image to be observed, photographed and sent to a computer, telescopes work by employing one or
Rapid City, South Dakota
Rapid City is the second most populous city in South Dakota and the county seat of Pennington County. Named after Rapid Creek, on which the city is established, it is set against the eastern slope of the Black Hills mountain range; the population was 67,956 as of the 2010 Census. Known as the "Gateway to the Black Hills" due to its location and the "City of Presidents" because of the life-size bronze president statues located downtown. Rapid City is split by a low mountain ridge that divides the eastern parts of the city. Ellsworth Air Force Base is located on the outskirts of the city. Camp Rapid, a part of the South Dakota Army National Guard, is located in the western part of the city. Rapid City is home to popular attractions like Art Alley, Dinosaur Park, the City of Presidents walking tour, Chapel in the Hills, Storybook Island, Main Street Square and more; the historic "Old West" town of Deadwood is nearby. In the neighboring Black Hills are the popular tourist attractions of Mount Rushmore, the Crazy Horse Memorial, Custer State Park, Wind Cave National Park, Jewel Cave National Monument, the museum at the Black Hills Institute of Geological Research, to the east of the city is Badlands National Park.
The public discovery of gold in 1874 by the Black Hills Expedition brought a mass influx of settlers into the Black Hills region of South Dakota. Rapid City was founded, known as "Hay Camp", in 1876 by a group of disappointed miners, who promoted their new city as the "Gateway to the Black Hills", a nickname the city now shares with neighboring Box Elder. John Richard Brennan and Samuel Scott, with a small group of men, laid out the site of the present Rapid City in February 1876, named for the spring-fed Rapid Creek that flows through it. A square mile was measured off and the six blocks in the center were designated as a business section. Committees were appointed to bring in prospective merchants and their families to locate in the new settlement; the city soon began selling supplies to pioneers. Its location on the edge of the Plains and Hills and its large river valley made it the natural hub of railroads arriving in the late 1880s from both the south and east. By 1900, Rapid City had survived a boom and bust and was establishing itself as an important regional trade center for the upper midwest.
Although the Black Hills became a popular tourist destination in the late 1890s, it was a combination of local efforts, the popularity of the automobile, construction of improved highways that brought tourists to the Black Hills in large numbers after World War I. Gutzon Borglum a famous sculptor, began work on Mount Rushmore in 1927 and his son, Lincoln Borglum, continued the carving of the presidents' faces in rock following his father's death in 1941; the work was halted due to pressures leading to the US entry into World War II and the massive sculpture was declared complete in 1941. Although tourism sustained the city throughout the Great Depression of the 1930s, the gasoline rationing of World War II had a devastating effect on the tourist industry in the town, but this was more than made up for by the war-related growth. In 1930, the Rapid City Chamber of Commerce sent a letter inviting Al Capone to live in the Black Hills. South Dakota's governor did not support the idea, neither did Capone, as he declined to relocate to the area.
The city benefited from the opening of Rapid City Army Air Base Ellsworth Air Force Base, an Army Air Corps training base. As a result, the population of the area nearly doubled between 1940 and 1948, from 14,000 to nearly 27,000 people. Military families and civilian personnel soon took every available living space in town, mobile home parks proliferated. Rapid City businesses profited from the military payroll. During the Cold War, missile installations proliferated in the area: a series of Nike Air Defense sites were constructed around Ellsworth in the 1950s. In the early 60s the construction of three Titan missile launch sites containing a total of nine Titan I missiles in the general vicinity of Rapid City took place. Beginning in November 1963, the land for a hundred miles east and northwest of the city was dotted with 150 Minuteman missile silos and 15 launch command centers, all of which were deactivated in the early 1990s. In 1949, city officials envisioned the city as a retail and wholesale trade center for the region and designed a plan for growth that focused on a civic center, more downtown parking places, new schools, paved streets.
A construction boom continued into the 1950s. Growth slowed in the 1960s, but the worst natural disaster in South Dakota history, the Black Hills Flood of 1972, led to another building boom a decade later. On June 9, 1972, heavy rains caused massive flash flooding along the course of Rapid Creek through the city. 238 people lost more than $100 million in property was destroyed. The devastation of the flood and the outpouring of private donations and millions of dollars in federal aid led to the completion of one big part of the 1949 plan: clearing the area along the Rapid Creek and making it a public park. New homes and businesses were constructed to replace those, destroyed. Rushmore Plaza Civic Center and a new Central High School were built in part of the area, cleared; the new Central High School opened in 1978, with the graduating class in that year straddling both the original Central and the new Central. The rebuilding in part insulated Rapid City from the drop in automotive tourism caused by the Oil Embargo in 1974, but tourism was depressed for most of a decade.
In 1978, Rushmore Mall was built on the north edge of the city, adding to the city's position as a retail shoppin
An observatory is a location used for observing terrestrial or celestial events. Astronomy, climatology/meteorology, geophysical and volcanology are examples of disciplines for which observatories have been constructed. Observatories were as simple as containing an astronomical sextant or Stonehenge. Astronomical observatories are divided into four categories: space-based, ground-based, underground-based. Ground-based observatories, located on the surface of Earth, are used to make observations in the radio and visible light portions of the electromagnetic spectrum. Most optical telescopes are housed within a dome or similar structure, to protect the delicate instruments from the elements. Telescope domes have a slit or other opening in the roof that can be opened during observing, closed when the telescope is not in use. In most cases, the entire upper portion of the telescope dome can be rotated to allow the instrument to observe different sections of the night sky. Radio telescopes do not have domes.
For optical telescopes, most ground-based observatories are located far from major centers of population, to avoid the effects of light pollution. The ideal locations for modern observatories are sites that have dark skies, a large percentage of clear nights per year, dry air, are at high elevations. At high elevations, the Earth's atmosphere is thinner, thereby minimizing the effects of atmospheric turbulence and resulting in better astronomical "seeing". Sites that meet the above criteria for modern observatories include the southwestern United States, Canary Islands, the Andes, high mountains in Mexico such as Sierra Negra. A newly emerging site which should be added to this list is Mount Gargash. With an elevation of 3600 m above sea level, it is the home to the Iranian National Observatory and its 3.4m INO340 telescope. Major optical observatories include Mauna Kea Observatory and Kitt Peak National Observatory in the US, Roque de los Muchachos Observatory and Calar Alto Observatory in Spain, Paranal Observatory in Chile.
Specific research study performed in 2009 shows that the best possible location for ground-based observatory on Earth is Ridge A — a place in the central part of Eastern Antarctica. This location provides the least atmospheric disturbances and best visibility. Beginning in 1930s, radio telescopes have been built for use in the field of radio astronomy to observe the Universe in the radio portion of the electromagnetic spectrum; such an instrument, or collection of instruments, with supporting facilities such as control centres, visitor housing, data reduction centers, and/or maintenance facilities are called radio observatories. Radio observatories are located far from major population centers to avoid electromagnetic interference from radio, TV, other EMI emitting devices, but unlike optical observatories, radio observatories can be placed in valleys for further EMI shielding; some of the world's major radio observatories include the Socorro, in New Mexico, United States, Jodrell Bank in the UK, Arecibo in Puerto Rico, Parkes in New South Wales and Chajnantor in Chile.
Since the mid-20th century, a number of astronomical observatories have been constructed at high altitudes, above 4,000–5,000 m. The largest and most notable of these is the Mauna Kea Observatory, located near the summit of a 4,205 m volcano in Hawaiʻi; the Chacaltaya Astrophysical Observatory in Bolivia, at 5,230 m, was the world's highest permanent astronomical observatory from the time of its construction during the 1940s until 2009. It has now been surpassed by the new University of Tokyo Atacama Observatory, an optical-infrared telescope on a remote 5,640 m mountaintop in the Atacama Desert of Chile; the oldest proto-observatories, in the sense of a private observation post, Wurdi Youang, Australia Zorats Karer, Armenia Loughcrew, Ireland Newgrange, Ireland Stonehenge, Great Britain Quito Astronomical Observatory, located 12 minutes south of the Equator in Quito, Ecuador. Chankillo, Peru El Caracol, Mexico Abu Simbel, Egypt Kokino, Republic of Macedonia Observatory at Rhodes, Greece Goseck circle, Germany Ujjain, India Arkaim, Russia Cheomseongdae, South Korea Angkor Wat, CambodiaThe oldest true observatories, in the sense of a specialized research institute, include: 825 AD: Al-Shammisiyyah observatory, Iraq 869: Mahodayapuram Observatory, India 1259: Maragheh observatory, Iran 1276: Gaocheng Astronomical Observatory, China 1420: Ulugh Beg Observatory, Uzbekistan 1442: Beijing Ancient Observatory, China 1577: Constantinople Observatory of Taqi ad-Din, Turkey 1580: Uraniborg, Denmark 1581: Stjerneborg, Denmark 1642: Panzano Observatory, Italy 1642: Round Tower, Denmark 1633: Leiden Observatory, Netherlands 1667: Paris Observatory, France 1675: Royal Greenwich Observatory, England 1695: Sukharev Tower, Russia 1711: Berlin Observatory, Germany 1724: Jantar Mantar, India 1753: Stockholm Observatory, Sweden 1753: Vilnius University Observatory, Lithuania 1753: Navy Royal Institute and Observatory, Spain 1759: Trieste Observatory, Italy 1757: Macfarlane Observatory, Scotland 1759: Turin Observatory, Italy 1764: Brera Astronomical Observatory, Italy 1765: Mohr Observatory, Indonesia 1774: Vatican Observatory, Vatican 1785: Dunsink Observatory, Ireland 1786: Madras Observatory, India 1789: Armagh Observatory, Northern Ireland 1790: Real Observatorio de Madrid, Spain, 1803: National Astronomical Observatory, Bogotá, Colombia.
1811: Tartu Old Observatory, Estonia 1812: Astronomical Observatory of Capodimonte, Italy 1830/1842: Depot of Charts & Instruments
Astronomy is a natural science that studies celestial objects and phenomena. It applies mathematics and chemistry in an effort to explain the origin of those objects and phenomena and their evolution. Objects of interest include planets, stars, nebulae and comets. More all phenomena that originate outside Earth's atmosphere are within the purview of astronomy. A related but distinct subject is physical cosmology, the study of the Universe as a whole. Astronomy is one of the oldest of the natural sciences; the early civilizations in recorded history, such as the Babylonians, Indians, Nubians, Chinese and many ancient indigenous peoples of the Americas, performed methodical observations of the night sky. Astronomy has included disciplines as diverse as astrometry, celestial navigation, observational astronomy, the making of calendars, but professional astronomy is now considered to be synonymous with astrophysics. Professional astronomy is split into theoretical branches. Observational astronomy is focused on acquiring data from observations of astronomical objects, analyzed using basic principles of physics.
Theoretical astronomy is oriented toward the development of computer or analytical models to describe astronomical objects and phenomena. The two fields complement each other, with theoretical astronomy seeking to explain observational results and observations being used to confirm theoretical results. Astronomy is one of the few sciences in which amateurs still play an active role in the discovery and observation of transient events. Amateur astronomers have made and contributed to many important astronomical discoveries, such as finding new comets. Astronomy means "law of the stars". Astronomy should not be confused with astrology, the belief system which claims that human affairs are correlated with the positions of celestial objects. Although the two fields share a common origin, they are now distinct. Both of the terms "astronomy" and "astrophysics" may be used to refer to the same subject. Based on strict dictionary definitions, "astronomy" refers to "the study of objects and matter outside the Earth's atmosphere and of their physical and chemical properties," while "astrophysics" refers to the branch of astronomy dealing with "the behavior, physical properties, dynamic processes of celestial objects and phenomena."
In some cases, as in the introduction of the introductory textbook The Physical Universe by Frank Shu, "astronomy" may be used to describe the qualitative study of the subject, whereas "astrophysics" is used to describe the physics-oriented version of the subject. However, since most modern astronomical research deals with subjects related to physics, modern astronomy could be called astrophysics; some fields, such as astrometry, are purely astronomy rather than astrophysics. Various departments in which scientists carry out research on this subject may use "astronomy" and "astrophysics" depending on whether the department is affiliated with a physics department, many professional astronomers have physics rather than astronomy degrees; some titles of the leading scientific journals in this field include The Astronomical Journal, The Astrophysical Journal, Astronomy and Astrophysics. In early historic times, astronomy only consisted of the observation and predictions of the motions of objects visible to the naked eye.
In some locations, early cultures assembled massive artifacts that had some astronomical purpose. In addition to their ceremonial uses, these observatories could be employed to determine the seasons, an important factor in knowing when to plant crops and in understanding the length of the year. Before tools such as the telescope were invented, early study of the stars was conducted using the naked eye; as civilizations developed, most notably in Mesopotamia, Persia, China and Central America, astronomical observatories were assembled and ideas on the nature of the Universe began to develop. Most early astronomy consisted of mapping the positions of the stars and planets, a science now referred to as astrometry. From these observations, early ideas about the motions of the planets were formed, the nature of the Sun and the Earth in the Universe were explored philosophically; the Earth was believed to be the center of the Universe with the Sun, the Moon and the stars rotating around it. This is known as the geocentric model of the Ptolemaic system, named after Ptolemy.
A important early development was the beginning of mathematical and scientific astronomy, which began among the Babylonians, who laid the foundations for the astronomical traditions that developed in many other civilizations. The Babylonians discovered. Following the Babylonians, significant advances in astronomy were made in ancient Greece and the Hellenistic world. Greek astronomy is characterized from the start by seeking a rational, physical explanation for celestial phenomena. In the 3rd century BC, Aristarchus of Samos estimated the size and distance of the Moon and Sun, he proposed a model of the Solar System where the Earth and planets rotated around the Sun, now called the heliocentric model. In the 2nd century BC, Hipparchus discovered precession, calculated the size and distance of the Moon and inven